In the medical field it is often necessary to mix two separate components such as a mixture of a drug and a diluent or a mixture of dextrose and amino acids. Such mixtures must often be stored separately. In the case of amino acids and dextrose, for example, the mixture is not stable over long time periods. Such instability may also be the case for the mixture of a drug and a diluent. Also, some drugs lose their efficacy when stored in a liquid diluent and must be stored dry, such as a powdered drug stored in a drug vial of standard construction. Some components are sterilized differently and for this reason may be combined only after each component is separately sterilized. For example, most liquid diluents, such as sterile water or sterile dextrose solution, are sterilized by steam sterilization, or autoclaving. The heat generated during such a sterilization procedure may destroy the efficacy of many powdered drugs which must be sterilized by other means.
In addition to maintaining two components separately during storage, there is a need for a quick and easy means for selectively mixing the two components, in a closed system under sterile conditions. It is known to provide a multiple chamber container of flexible plastic sheets with a heat seal dividing the container into two or more chambers. Such is shown, for example, in U.S. Pat. No. 4,396,383 to Hart, assigned to the assignee of the present invention, directed to a container which employs frangible valves between the heat seal to allow for selective communication and mixing between the two components stored in the two chambers.
Other means for establishing a closed system for the separate storage and selective mixing of two components is shown in the copending U.S. patent application of Pearson, et al., Ser. No. 365,942 filed Apr. 6, 1982 and assigned to the assignee of the present invention. The device shown therein utilizes a preferably plastic junction about the end portions of container and chamber access means to allow for the separate storage and selective mixing of two components such as a powdered drug and a liquid diluent.
It is desirable to provide a multiple chamber closed system which does not require additional elements integrated into the container to form the openable valve between the compartments. Such are shown, for example, in U.S. Pat. Nos. 3,950,158, 4,000,996 and 4,226,330. In each of these patents there is disclosed a multiple chamber container which has a line of weakness, such as a score line in plastic material, which breaks upon the application of pressure.
Tear tabs or tear strips for plastic packaging are also known, such as shown in U.S. Pat. No. 2,991,000. Such tear tabs provide ready access to the contents of a container but also involve the use of a relatively complicated seal structure. U.S. Pat. No. 3,983,994 discloses a peelable seal broken by pulling upon tabs located outside of the container.
Rupturable seal lines such as shown in the above named patents may all suffer from the common problems of rupturing before communication between the two chambers is intended. The rupturable seal lines are designed to be weaker than the remainder of the container so that upon the application of force the rupture line breaks first.
It is also desirable to provide a multiple chamber closed container having a selectively openable seal line between the chambers which when closed virtually eliminates the transmission of moisture into one of the chambers from either outside of the container or from the other chamber. Such a requirement may be necessary when, for example, a powdered drug is stored in one of the chambers of the container.